Remove work from the main thread #157

I've been looking at the Lighthouse report for my viewer on 2b2t spawn (local, downloaded file), and the performance was terrible. Some of my findings after messing with the code:

• Making all event listeners (controls.js) passive reduces input lag
• AO is slower (models.js:202)
• Basic material is faster (entity.js:174, worldrenderer.js:16)
• With the rendering faster, the map also loaded faster

The last one is the most important one and the reason why some parts (rendering, io, etc) should be in another thread.

Here's an implementation example from a blog

Here's a test of time to load all chunks in 6 render distance. 1.15.1: 1m 51s My optimized version: 0m 28s

All done on a paper 1.12 server, on this world